In an afternoon conference call with the American Lung Assn. and other public health groups, Obama argued that restrictions on power plant emissions would help children with asthma and other health problems exacerbated by carbon pollution.

“These claims are debunked when you actually give workers and businesses the tools that they need to innovate,” Obama said, pointing to the technological advances in fuel-efficient cars and appliances encouraged by government over the past few years.

“In America,” he said, “we do not have to choose between the health of our economy and the health of our kids.”

He placed the call from the Oval Office, making it his only public business on Monday before leaving for a week in Europe.

With the new proposal, Obama hopes to cut greenhouse gases by 30% from their 2005 level by 2030.

The unveiling on Monday begins a one-year period of comment and review, during which business interests and advocates will lobby for change. As expected, it set off a fresh debate over the wisdom of the regulation.

Business leaders and Republican skeptics began to critique the particulars of the plan. Before the rule was unveiled, the U.S. Chamber of Commerce estimated it would cost the economy $50 billion annually.

The EPA, meanwhile, said that, in the year 2030, the reductions in carbon pollution would result in “net climate and health benefits of $48 billion to $82 billion,” according to the agency’s proposal.

Administration officials also argued that the plan is sensitive to the special needs in some heavily coal-reliant states. The plan is designed give each state a menu of options for meeting their specific targets, officials pointed out, noting that each is based on the particular state’s fuel mix.

The Obama administration will seek to cut greenhouse gas emissions from existing power plants 30% from 2005 levels by 2030, potentially one of the biggest steps any country has taken to confront climate change, people familiar with the plan said Sunday.

Amid heightened speculation about whether he will seek the Democratic presidential nomination, Vice President Joe Biden remains at least a month from a decision and has largely left preparatory work to a small circle of trusted longtime aides.

Perched in his wheelchair, "Big Jim" Blake confidently rolls the wooden floors of his old shoot-'em-up saloon, founded here in 1893. The history of the Cowboy Bar is populated with drifters, outlaws and outliers, and its present proprietor brims with wild yarns and tall tales.

President Obama will impose even steeper cuts on greenhouse gas emissions from U.S. power plants than previously expected, White House officials said early Sunday, in what the president called the most significant step the country has ever taken to fight global warming.